/*
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 *    AddExpression.java
 *    Copyright (C) 2000-2012 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.filters.unsupervised.attribute;

import java.util.Enumeration;
import java.util.Vector;

import weka.core.Attribute;
import weka.core.Capabilities;
import weka.core.Capabilities.Capability;
import weka.core.DenseInstance;
import weka.core.Instance;
import weka.core.Instances;
import weka.core.Option;
import weka.core.OptionHandler;
import weka.core.SparseInstance;
import weka.core.Utils;
import weka.core.WeightedAttributesHandler;
import weka.core.WeightedInstancesHandler;
import weka.core.expressionlanguage.common.IfElseMacro;
import weka.core.expressionlanguage.common.JavaMacro;
import weka.core.expressionlanguage.common.MacroDeclarationsCompositor;
import weka.core.expressionlanguage.common.MathFunctions;
import weka.core.expressionlanguage.common.Primitives.DoubleExpression;
import weka.core.expressionlanguage.core.Node;
import weka.core.expressionlanguage.parser.Parser;
import weka.core.expressionlanguage.weka.InstancesHelper;
import weka.filters.Filter;
import weka.filters.StreamableFilter;
import weka.filters.UnsupervisedFilter;

/**
 * <!-- globalinfo-start --> An instance filter that creates a new attribute by
 * applying a mathematical expression to existing attributes. The expression can
 * contain attribute references and numeric constants. Supported operators are
 * :<br/>
 * +, -, *, /, ^, log, abs, cos, exp, sqrt, floor, ceil, rint, tan, sin, (,
 * )<br/>
 * Attributes are specified by prefixing with 'a', eg. a7 is attribute number 7
 * (starting from 1).<br/>
 * Example expression : a1^2*a5/log(a7*4.0).
 * <p/>
 * <!-- globalinfo-end -->
 * 
 * <!-- options-start --> Valid options are:
 * <p/>
 * 
 * <pre>
 * -E &lt;expression&gt;
 *  Specify the expression to apply. Eg a1^2*a5/log(a7*4.0).
 *  Supported opperators: ,+, -, *, /, ^, log, abs, cos, 
 *  exp, sqrt, floor, ceil, rint, tan, sin, (, )
 *  (default: 0.0)
 * </pre>
 * 
 * <pre>
 * -N &lt;name&gt;
 *  Specify the name for the new attribute. (default is the expression provided with -E)
 * </pre>
 * 
 * <pre>
 * -D
 *  Debug. Names attribute with the postfix parse of the expression.
 * </pre>
 * 
 * <!-- options-end -->
 * 
 * @author Mark Hall (mhall@cs.waikato.ac.nz)
 * @version $Revision$
 */
public class AddExpression extends Filter implements UnsupervisedFilter, StreamableFilter, OptionHandler, WeightedInstancesHandler, WeightedAttributesHandler {

    /** for serialization */
    static final long serialVersionUID = 402130384261736245L;

    /** The infix expression */
    private String m_infixExpression = "0.0";

    /**
     * Name of the new attribute. "expression" length string will use the provided
     * expression as the new attribute name
     */
    private String m_attributeName = "expression";

    /**
     * If true, makes the attribute name equal to the postfix parse of the
     * expression
     */
    private boolean m_Debug = false;

    private DoubleExpression m_Expression = null;

    private InstancesHelper m_InstancesHelper;

    /**
     * Returns a string describing this filter
     * 
     * @return a description of the filter suitable for displaying in the
     *         explorer/experimenter gui
     */
    public String globalInfo() {
        return "An instance filter that creates a new attribute by applying a " + "mathematical expression to existing attributes. The expression " + "can contain attribute references and numeric constants. Supported " + "operators are :\n" + "+, -, *, /, ^, log, abs, cos, exp, sqrt, floor, ceil, rint, tan, " + "sin, (, )\n" + "Attributes are specified by prefixing with 'a', eg. a7 is " + "attribute number 7 (starting from 1).\n" + "Example expression : a1^2*a5/log(a7*4.0).";
    }

    /**
     * Returns an enumeration describing the available options.
     * 
     * @return an enumeration of all the available options.
     */
    @Override
    public Enumeration<Option> listOptions() {

        Vector<Option> newVector = new Vector<Option>(3);

        newVector.addElement(new Option("\tSpecify the expression to apply. Eg a1^2*a5/log(a7*4.0)." + "\n\tSupported opperators: ,+, -, *, /, ^, log, abs, cos, " + "\n\texp, sqrt, floor, ceil, rint, tan, sin, (, )" + "\n\t(default: a1^2)", "E", 1, "-E <expression>"));

        newVector.addElement(new Option("\tSpecify the name for the new attribute. (default is the " + "expression provided with -E)", "N", 1, "-N <name>"));

        newVector.addElement(new Option("\tDebug. Names attribute with the postfix parse of the " + "expression.", "D", 0, "-D"));

        return newVector.elements();
    }

    /**
     * Parses a given list of options.
     * <p/>
     * 
     * <!-- options-start --> Valid options are:
     * <p/>
     * 
     * <pre>
     * -E &lt;expression&gt;
     *  Specify the expression to apply. Eg a1^2*a5/log(a7*4.0).
     *  Supported opperators: ,+, -, *, /, ^, log, abs, cos, 
     *  exp, sqrt, floor, ceil, rint, tan, sin, (, )
     *  (default: a1^2)
     * </pre>
     * 
     * <pre>
     * -N &lt;name&gt;
     *  Specify the name for the new attribute. (default is the expression provided with -E)
     * </pre>
     * 
     * <pre>
     * -D
     *  Debug. Names attribute with the postfix parse of the expression.
     * </pre>
     * 
     * <!-- options-end -->
     * 
     * @param options the list of options as an array of strings
     * @throws Exception if an option is not supported
     */
    @Override
    public void setOptions(String[] options) throws Exception {
        String expString = Utils.getOption('E', options);
        if (expString.length() != 0) {
            setExpression(expString);
        } else {
            setExpression("a1^2");
        }

        String name = Utils.getOption('N', options);
        if (name.length() != 0) {
            setName(name);
        }

        setDebug(Utils.getFlag('D', options));

        Utils.checkForRemainingOptions(options);
    }

    /**
     * Gets the current settings of the filter.
     * 
     * @return an array of strings suitable for passing to setOptions
     */
    @Override
    public String[] getOptions() {

        Vector<String> options = new Vector<String>();

        options.add("-E");
        options.add(getExpression());
        options.add("-N");
        options.add(getName());

        if (getDebug()) {
            options.add("-D");
        }

        return options.toArray(new String[0]);
    }

    /**
     * Returns the tip text for this property
     * 
     * @return tip text for this property suitable for displaying in the
     *         explorer/experimenter gui
     */
    public String nameTipText() {
        return "Set the name of the new attribute.";
    }

    /**
     * Set the name for the new attribute. The string "expression" can be used to
     * make the name of the new attribute equal to the expression provided.
     * 
     * @param name the name of the new attribute
     */
    public void setName(String name) {
        m_attributeName = name;
    }

    /**
     * Returns the name of the new attribute
     * 
     * @return the name of the new attribute
     */
    public String getName() {
        return m_attributeName;
    }

    /**
     * Returns the tip text for this property
     * 
     * @return tip text for this property suitable for displaying in the
     *         explorer/experimenter gui
     */
    public String debugTipText() {
        return "Set debug mode. If true then the new attribute will be named with " + "the postfix parse of the supplied expression.";
    }

    /**
     * Set debug mode. Causes the new attribute to be named with the postfix parse
     * of the expression
     * 
     * @param d true if debug mode is to be used
     */
    public void setDebug(boolean d) {
        m_Debug = d;
    }

    /**
     * Gets whether debug is set
     * 
     * @return true if debug is set
     */
    public boolean getDebug() {
        return m_Debug;
    }

    /**
     * Returns the tip text for this property
     * 
     * @return tip text for this property suitable for displaying in the
     *         explorer/experimenter gui
     */
    public String expressionTipText() {
        return "Set the math expression to apply. Eg. a1^2*a5/log(a7*4.0)";
    }

    /**
     * Set the expression to apply
     * 
     * @param expr a mathematical expression to apply
     */
    public void setExpression(String expr) {
        m_infixExpression = expr;
    }

    /**
     * Get the expression
     * 
     * @return the expression
     */
    public String getExpression() {
        return m_infixExpression;
    }

    /**
     * Returns the Capabilities of this filter.
     * 
     * @return the capabilities of this object
     * @see Capabilities
     */
    @Override
    public Capabilities getCapabilities() {
        Capabilities result = super.getCapabilities();
        result.disableAll();

        // attributes
        result.enableAllAttributes();
        result.enable(Capability.MISSING_VALUES);

        // class
        result.enableAllClasses();
        result.enable(Capability.MISSING_CLASS_VALUES);
        result.enable(Capability.NO_CLASS);

        return result;
    }

    /**
     * Sets the format of the input instances.
     * 
     * @param instanceInfo an Instances object containing the input instance
     *                     structure (any instances contained in the object are
     *                     ignored - only the structure is required).
     * @return true if the outputFormat may be collected immediately
     * @throws Exception if the format couldn't be set successfully
     */
    @Override
    public boolean setInputFormat(Instances instanceInfo) throws Exception {

        m_InstancesHelper = new InstancesHelper(instanceInfo);
        Node node = Parser.parse(
                // expressions string
                m_infixExpression,
                // variables
                m_InstancesHelper,
                // macros
                new MacroDeclarationsCompositor(m_InstancesHelper, new MathFunctions(), new IfElseMacro(), new JavaMacro()));

        if (!(node instanceof DoubleExpression))
            throw new Exception("Expression must be of double type!");

        m_Expression = (DoubleExpression) node;

        super.setInputFormat(instanceInfo);

        Instances outputFormat = new Instances(instanceInfo, 0);
        Attribute newAttribute;
        if (m_attributeName.compareTo("expression") != 0) {
            newAttribute = new Attribute(m_attributeName);
        } else {
            newAttribute = new Attribute(m_infixExpression);
        }
        outputFormat.insertAttributeAt(newAttribute, instanceInfo.numAttributes());
        setOutputFormat(outputFormat);
        return true;
    }

    /**
     * Input an instance for filtering. Ordinarily the instance is processed and
     * made available for output immediately. Some filters require all instances be
     * read before producing output.
     * 
     * @param instance the input instance
     * @return true if the filtered instance may now be collected with output().
     * @throws IllegalStateException if no input format has been defined.
     * @throws Exception             if there was a problem during the filtering.
     */
    @Override
    public boolean input(Instance instance) throws Exception {

        if (getInputFormat() == null) {
            throw new IllegalStateException("No input instance format defined");
        }
        if (m_NewBatch) {
            resetQueue();
            m_NewBatch = false;
        }

        double[] vals = new double[instance.numAttributes() + 1];
        System.arraycopy(instance.toDoubleArray(), 0, vals, 0, instance.numAttributes());

        m_InstancesHelper.setInstance(instance);
        vals[vals.length - 1] = m_Expression.evaluate();
        if (m_InstancesHelper.missingAccessed())
            vals[vals.length - 1] = Utils.missingValue();

        Instance inst = null;
        if (instance instanceof SparseInstance) {
            inst = new SparseInstance(instance.weight(), vals);
        } else {
            inst = new DenseInstance(instance.weight(), vals);
        }

        copyValues(inst, false, instance.dataset(), outputFormatPeek());

        push(inst); // No need to copy instance
        return true;
    }

    /**
     * Main method for testing this class.
     * 
     * @param args should contain arguments to the filter: use -h for help
     */
    public static void main(String[] args) {
        runFilter(new AddExpression(), args);
    }
}
